Anaerobic Hydrolytic Degradation of Cefpodoxime Proxetil in the Presence of UV Irradiation and in Darkness: Kinetics and pH Effect

Abstract

In this study, the anaerobic hydrolytic degradation of cefpodoxime proxetil (CP) in the presence of UV-light irradiation and in darkness has been studied at Britton-Robinson (B-R) buffer solutions (pH 2.5-11) by cyclic and square-wave voltammetry techniques. By means of these electrochemical techniques, the hydrolytic degradation of CP was successfully followed. The pH effect on this degradation was also investigated. In darkness, the decrease in the peak current of CP was not practically observed at the acidic and physiological pHs (2.5, 5.0 and 7.4). But, in the basic medium (pH 9.0 and 11.0), a decrease in the peak current was detected. On the other hand, UV irradiation caused a decrease in the peak current of CP and a positive shift in its cathodic peak potential. Under the UV irradiation, the maximum stability of CP was observed in B-R buffer of pH 5. It has been determined that UV irradiation has a great effect on hydrolytic degradation of CP at basic medium. On the other hand, at pHs >= 7.4, a new peak has been also obtained at more positive potential than that of the first reduction peak of CP. The current of this peak increases by increasing UV irradiation time. This peak could be assigned to the reduction of a new electroactive product which was formed from the hydrolytic degradation of CP under UV irradiation. The hydrolytic degradation reaction of CP followed pseudo-first order kinetics.